Switch contact construction



July 7, 1959 s. LINDELL ETAL 2,894,101

SWITCH CONTACT CONSTRUCTION Filed Jan. 20, 1958 7 Sheets-sheaf 1 13 I l.4 RUBBER g J42 BUMPER In! --fi V IO 5 ardllmaell,

511133 7, 1959 s. l. LINDELL ETAL SWITCH CONTACT CONSTRUCTION 7Sheets-Sheet 2 Filed Jan. 20, 1958 All; V/

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July 7, 1959 s. I. LINDELL ET AL SWITCH CONTACT CONSTRUCTION 7Sheets-Sheet 3 Filed Jan. 20, 1958 INVENT R5- July 7, 1959 I s. I.LINDELL ET AL SWITCH CONTACT CONSTRUCTION 7 Sheets-Sheet 4 Filed Jan.20, 1958 n a MM 3 a 11: M g N .0 NW .11 Nm QN.\\\ hm v R\\ Mb 7, 1959 s.l. LINDELL ETAL SWITCH CONTACT CONSTRUCTION 7 Sheets-Sheet 6 Filed Jan.20, 1958 2,894,101 swrrcn CONTACT CONSTRUCTION Sigurd I. Lindell,Chicago, and John S. Ferguson, Glenview, 111., assignors to S dz CElectric (Zompany, (ihiu cago, 111., a corporation of DelawareApplication January 20, 1958, Serial No. 709,863

' 44 Claims. (Cl. 200-166) This invention relates, generally, to highcurrent capacity switches and it has particular relation to theconstruction of contacts for such switches, especially of the typeillustrated in US. Patent No. 2,710,897, issued June 14, 1955, althoughit is not limited for use with the switch there shown. This applicationis a continuationin-part of application Serial No. 613,401, filedOctober 2, 1956, now abandoned.

Among the objects of this invention are: To provide a switch contactconstruction in which the contact engagement is obtained under pressurewith minimum effort being required to effect engagement anddisengagement and permitting some lateral and angular misalignment; toemploy relatively massive contact fingers to withstand the flow of shortcircuit current without permanent distortion or damage; to direct thecurrent flow to the contact fingers along paths where the magneticfields generated thereby act to increase the contact pressure; to employa pair of U-shaped conductors as part of the contact construction withtheir outer arms rigidly mounted at their outer ends and their innerarms biased toward each other and carrying the contact fingers forengaging opposite sides of a switch blade which enters and leaves at theside at which the contact fingers are located; to prestress the innerarms toward each other by a floating spring arrangement in such mannerthat the contact fingers are independently flexible and independentlyspring biased; and to provide a relatively long and narrow convexcontact surface on each contact finger for engaging a flat surface of aswitch blade with a wiping action along a narrow path substantially inthe direction of the blade movement while contact engagement is beingmade and broken to improve the cleaning action applied to the contactsurfaces and reduce the operating effort and provide essentially a linecontact engagement relatively unaffected by slight misalignment.

Additional objects of this invention are: To provide a switch contactconstruction of the character outlined above in which the switch blade,in closed position, constitutes an endwise extension of the inner armsof the U-shaped conductors and enters and leaves contact engagementtherewith transversely of these inner arms; to provide contact surfaceson the inner arms extending transversely thereof; to provide forconnecting a line conductor to the switch contact construction at alocation which is substantially a straight line extension of the switchblade in switch closed position; to mount the U- shaped conductors insuch manner that the path of the current from the line terminal to theswitch blade is in the form of a double loop to each side of the switchblade; to obtain high current carrying capacity by employing a pluralityof pairs of U-shaped conductors; to position the U-shaped conductorswith the portions that engage the switch blade facing outwardly; tolocate the U-shaped conductors with the contact portions facingoutwardly such that the magnetic forces incident to current flow tend tohold the switch blade in the closed position; and to adapt the switchcontactconstruction employing the U-shaped conductors for use with aswitch blade that is rotated about itslongitudinal axis into highpressure contact engagement. with the contact surfaces of the contactfingers.

Other objects of this invention will, in part, be obvious and in partappear hereinafter.

This invention is disclosed in the embodiment thereof shown in theaccompanying drawings and it comprises the features of construction,combination of elements and arrangement of parts that will beexemplified in the construction hereinafter set forth and the scope ofthe application of which will be indicated in the appended claims. I

For a more complete understanding of the nature and scope of thisinvention, reference can be had to the following detailed description,taken together with the accompanying drawings, in which:

Figure 1 is a view, in side elevation, of one pole of a high voltageswitch in which this invention is embodied;

Figure 2 is a vertical sectional view, at an enlarged scale, takengenerally along the line 22 of Figure 1;

Figure 3 is a view, similar to Figure 2, but showing only a portionthereof with the switch blade disengaged from the stationary contactassembly;

Figure 4 is a vertical sectional view, at an enlarged scale, takengenerally along the line 4-4 of Figure 3;

Figure 5 is a horizontal sectional view taken generally along the line55 of Figure 3;

Figure 6 is a horizontal sectional view taken generally along the line6-6 of Figure 3;

Figure 7 is a view, in side elevation, of one of the contact fingers,the showing being at an enlarged scale;

Figure 8 is a view, in front elevation, of the contact finger shown inFigure 7;

Figure 9 is a cross sectional view taken generally along the line 9-9 ofFigure 7;

Figure 10 is a sectional view taken generally along the line 1010 ofFigure 7; I

Figure 11 is a view, in side elevation, of a modified form of switchconstruction employing a switch blade that is rotatable about one endinto and out of sidewise engagement with the stationary contact of thepresent invention;

Figure 12 is a top plan view-of the contact construction shown in Figure11 with the switch blade in closed position;

Figure 13 is a vertical sectional view taken generally along the line13-13 of Figure 12;

Figure 14 is a view, similar to Figure 13, but show Figure 17 is a topplan view of a contact construction that is located within a switchblade comprising a pair of blade members the-inner sides of which arearranged to engage the outwardly facing contact surfaces of the contactfingers;

Figure 18 is a vertical sectional view taken generally along line 18-18of Figure 17;

Figure 19 is a view, similar to Figure 18, but showing the U-shapedconductors forming the contact fingers inverted with the arrangementbeing such that the magnetic forces incident to current flow tend tohold the switch blade in the closed position;

Figure 20 is a view, in end elevation, of a contact construction thatcan be employed in connection with a switch blade thatis arranged torotate about its 1ongitudinal axis into high pressure contactengagement, the construction being that shown in copending applicationSerial No. 704,397, filed December 23, 1957;

Figure 21 is a view, in side elevation, of the contact constructionshown in Figure 20;

Figure 22 is a top plan view of the contact construction shown inFigures 20 and 21; I

Figure 23 is a view, in end elevation, of a modified form of contactconstruction that can be employed in conjunction with a switch bladewhich is arranged to rotate about its longitudinal axis into highpressure switch closed position; and

Fgure 24 is a view, in side elevation, of the contact construction shownin Figure 23. i

.Referring now particularly to Figure 1 of the drawings, it will beobserved that the refere nce character designates, generally, a metallic.base carry l m PPerating mechanism 11 for rotating an intermediateinsulator 12 about avertical axis. Near the of .theybase 10 stationaryinsulators 13 are mounted. while the base 10 is shown as beinghorizontally mounted with the insulators 12 and 13 extending upwardlytherefrom, it will be understood that the base 10 can beverticallymounted and that it can also be mounted with the insulators 12 and 13depending therefrom.

The stationary insulators 13 carry tenninal brackets, shown generally at14, which are provided with terminal pads 15 to which suitableconnection can be made by high voltage conductors. The terminal brackets14 include upright sections 16 to the upper ends of which loadinterrupter devices, shown generally at 17, are secured. Since adetailed description of the load interrupter device 17 is set forth inPatent No. 2,710,897, above referred to, no further description thereofwill be set forth herein.

Contact engagement with the load interrupter devices 17 is provided bybow contacts 18 that are carried by the ends of a tubular switch member19 which is mounted intermediate its ends on the insulator 12 and isrotatable therewith through 90 from the switch open to the switch closedposition. Each load interrupter device 17 is provided with a dependingoperating arm, shown generally at 20, that is arranged to be engaged byan operator, shown generally at 21, at each end of the switch member 19,for effecting the operation of the respective load interrupter device 17in the proper timed sequence. The operator 21 preferably is formedintegrally with a switch fitting 22 that is secured to each end of thetubular switch member 19.

Also integrally formed with the switch fitting 221's a switch blade 25.It will be understood that each switch fitting 22 is provided with aswitch blade 25 and that they extend in opposite directions underneaththe tubular switch member 19 when the switch construction is arranged asillustrated in Figures 1, 2 and 3 of the drawings. In order to provide agood contact surface, each of the switch blades 25 is provided withsilver inserts 26 on opposite sides and each has a rounded leading edgeportion 27 to facilitate engagement with a stationary contact assembly28 which is carried by'the respective upright sections 16 of theterminal brackets 14. The present invention is directed particularly tothe construction of the stationary contact assembly 28.

It will be observed that the stationary contactassembly 28 includes aU-shaped contact support that is shown generally at 29 and has a centralmounting ear 30 provided with apertures 31 for receiving bolts to secureit to the upright sections 16. 'The contact support 29 is formedpreferably of brass and is relatively rigid so that its upstanding arms32 are relatively Secured by n'vets 33 to the arms 32 are shown inFigure 5, are split lengthwise '88 indica ed at 37 to provide twosections for independently supporting relatively massive contact fingers40 that preferably are silver plated copper fcrgings. As shown moreclearly in Figures 7 and 8 of the drawings, the contact fingers 40 areprovided with apertures 41 for receiving rivets 42 to hold them securelyto the inner sides of the respective portions of the inner branches 36.Each of the contact fingers 40 is provided with a raised portion 43having a convex contact surface 44 that is relatively long and narrow.The radius, indicated at 45, of the longitudinal contact surface isseveral times the radius, indicated at 46 in Figure 9, of the transversecontact surface. For example, the radius 45 may be of the order of 2%"while the radius 46 may be of the order of This, together with aninclined approach surface 47, facilitates the entry of the roundedleading edge portion 27 of the switch blade 25 between the convexcontact surfaces 44 of the four contact fingers 40. Should there be anyforeign material on the silver inserts 26, the same is removed as theswitch blade 25 rnovcs into the Switch closed position as shown inFigure 2 since the convex contact surfaces 44, being long and narrow,function like plows to clear away the foreign material and provide forgood contact engagement between the contact surfaces 44 and thecorresponding portions of the silver inserts 26.

The relationship between each convex contact surface 44 and therespective portion of the fiat surface of the insert 26 carried by theswitch blade 25 is illustrated more clearly in Figures 7 and 9. Becauseof the longitudinal curvature of the convex contact surface 44 somelongitudinal and angular misalignment of the switch blade 25 and thecontact fingers 40 can be tolerated without impairment of the contactefiiciency. This is due to the fact that the actual contact area canshift longitudinally while still maintaining engagement with therespective surface portion of the insert 25. Another advantage resultingfrom this construction is that each contact area remains substantiallycentrally located with respect to its contact finger. On flow of shortcircuit current there is a more uniform distribution of current flow andof the resultant heat generated. The relatively long and narrow convexcontact surface 44 wipes into what approaches a limited line contactengagement with the respective flat contact surface of the insert 26which facilitates high unit pressure contact engagement and elfic-ientcurrent transfer over an extended contact area,

It is desirable to prestress the contact fingers 40 toward each other.Since the ,U-Shaped conductors 35 inherently are resilient and since theends of the outer branches 34 are held stationary by the upstanding arms32, the inner branches 36 tend to move toward each other when they arebiased or spring loaded as described hereinafter. Such movement islimited by a spacer sleeve 50 and a loading pin 63, to be described,which are interposed between the facing sides of the inner branches 36as shown more clearly in Figures 2 and 3 of the drawings. The lengths ofthe spacer sleeve 50 and loading pin 63 are such that the distance 51between the convex contact surfaces 44 is slightly less than thedistance 52 between the outwardly facing surfaces of the silver inserts26. Thus, when the switch blade 25 is moved from the position shown inFigure 3 to the switch closed position shown in Figure 2, it is onlynecessary to exert sufficient efifort to overcome the spring bias andspread the contact fingers 40 apart a slight distancewhich is sufiicientto space the opposed faces of the inner branches 36 from the adjacentends of the spacer sleeves 50 as indicated at 53. The entire springforce transmitted to and tending to urge the contact fingers 40 towardeach other then is immediately available for urging the convex contactsurfaces 44 into small area high pressure contact engagement with thesurface of the silver inserts 26.

With a view to applying a spring biasing action to the essayist contactfingers 40 and for individually biasing them toward the switch blade 25,a floating spring arrangement is employed. For this purpose an equalizerbar 54 extends through a spacer sleeve 50 and through the inner branches36. As shown in Figures 2 and 3, the equalizer bar 54 projects into thespaces between the branches 34 and 36 of the U-shaped conductors 35where transversely extending pins 55 are provided having reduced centralsections 56 which interfit with the equalizer bar 54 and preventdisengagement of the loading pins 55. Underlying each loading pin 55 isa spring leaf 57 the outer ends of which are bifurcated and the extremeouter ends 58 turned inwardly to have small area high pressureengagement with the bottoms of slots 59 that are formed in the rearsides of the contact fingers 40. At the inner ends of the spring leaves57 they have contact engagement with convex surfaces 60, Figure 4, ofcollars 61 which bear against the outer sides of the inner branches 36and are held in place in an articulated arrangement by reduced endportions 62 of the loading pin 63, above referred to, which ispositioned between the inner branches 36 near the curved outer endsthereof joining the outer branches 34. Each end of the loading pin 63has a stepped section 64 interfitting with an aperture 65 in each of theinner branches 36 at the base of the slot 37 therein. Since the outerbranches 34 are resilient, the sides of the inner branches 36 facingeach other bear against shoulders 66 on the loading pin 63 and thus theyare spaced apart a definite distance.

Preferably the U-shaped conductors 35 are made sufficiently resilient tobe flexed by a relatively low force and the spring leaves 57 arestressed sufficiently to apply the required biasing action and the majorportion of the pressure against the inserts 26. In effect a three pointapplication of force is provided by the arrangement of the spring leaves57 reactmg against the loading pins 55. One point of support is appliedagainst the collar 61 at each end of the loading pin 63 while the othertwo points are provided by the small area 1nturned ends 58 reactingagainst the back of each contact finger 40. In this manner a limiteddegree of flexibility is provided for each of the contact fingers 40 andfor each of the arms of the bifurcated end portion of each spring leaf57.

The equalizer bar 54 and loading pin 63 provide an articulated loadingmechanism for the spring leaves 57. Since this mechanism interconnectsthe spring leaves 57 through the loading pins 55, the forces exertedthereby are equalized. It is then possible for the spring forces to beapplied equally to the contact fingers 40 even when the switch blade 25,within limits, is out of alignment with the switch contact assembly 28.

Thus a limited degree of misalignment, for example as much as Ms, can beaccommodated between the switch blade 25 and the contact fingers 40. Thereason for this is that the outer branches 34 of the U-shaped conductors35 have relatively great flexibility within the elastic lim1t of thematerial used and the inner branches 36 also have limited degrees ofindependent flexibility and because the equalizer bar 54 is unattachedto them and permits their movement relative to it. Moreover, theequalizer bar 54 transmits the displacement of one of the contactfingers 40 or the displacement of two of them on one of the innerbranches 36 to the other inner branch 36 and thereby to the contactfingers 40 carried thereby. Within the limits specified misalignment ofthe switch blade 25 can be accommodated without reduction in the sum ofthe individual contact pressures and without increasing the total effortrequired to move the switch blade 25 to and from the switch closedposition. Even though the flexing of the U-shaped conductors 35 awayfrom the centered position adds somewhat to the pressure on one side ofthe blade 25, an equal reduction takes place on the other side.

It will be observed that the contact fingers 40 are located at the outerends of the inner branches 36 and that the overlap of the switch blade25 with these contact fingers is relatively short. Since provision ismade for moving the switch blade 25 endwise into engagement with thecontact fingers 4i), only a minimum movement of the switch blade 25 isrequired after it has entered the contact assembly 28 to effect completeclosing of the switch in contra-distinction of the movement that wouldbe required if the switch blade 25 were moved into switch closedengagement from the opposite ends of the inner branches 36. Likewise,only a minimum of movement toward the open position is required todisengage the contact asembly 28 and to establish the required gapbefore actuation of the load interrupter devices 17 and the length ofthe switch blade 25 can be a minimum;

It will be observed that a current flow through-the inner branches 36 isin the same direction. As a result, the magnetic fields generated by thecurrent flow through these branches are such as to urge the innerbranches 36 toward each other. This is particularly true under shortcircuit conditions on flow of relatively heavy current. The current flowin the outer branches 34 is in a direction opposite to the current flowin the inner branches 36. As a result, the magnetic forces producedthereby act in such manner as to urge the inner branches 36 away fromthe outer branches 34. Since the outer ends of the latter are heldstationary by the relatively rigid arms 32 of the contact support 29, astill further force is provided for increasing the contact pressureapplied by the contact fingers 40 to the contact surfaces of the switchblade 25, more particularly to the surfaces of the silver inserts 26.These forces also momentarily deform the surfaces of the inserts 26 toenlarge the area of contact engagement during short circuit conditions.

As pointed out, the shoulders 66 of the loading pin 63 space the lefthand ends of the inner branches 36 a fixed distance apart. Under shortcircuit conditions these shoulders provide relatively fixed fulcrumsabout which the inner branches 36 pivot. Thus maximum force is exertedagainst the inserts 26 on opposite sides of the switch blade 52 underthese conditions.

The contact fingers 40 are subject to substantial mechanical shock whenthe switch blade 25 is moved rapidly to switch closed position,particularly when it enters in misaligned position. Where their contactsurfaces are in engagement with the inserts 26, they may be subject to ahigh rate of heat generation during short circuit conditions. Because oftheir relatively massive construction and because of the other statedfeatures of Contact construction, the contact fingers 4A) are capable ofwithstanding such shock and heat generation.

With a view to reducing mechanical shock in closing of the switch,resilient bumpers 70 of rubber or the like are carried by each of theswitch fittings 22. They are arranged to engage one of the arms 32 ofthe contact supports 29, as shown in Figure 2, and prevent metal tometal contact. The bumpers 70 also function to determine the finalpositions of the inserts 26 relative to the contact surfaces 44 of thecontact fingers 40.

Because of the prestressed arrangement of the contact fingers 40 throughthe agency of the spacer sleeve 50 and due to the particular convexcurvature of the contact surface 44 with the radius 45 in thelongitudinal direction being substantially greater than the radius 46 inthe transverse direction, the drag is reduced and a minimum of effort isrequired to move the switch blade 25 into and out of the switch closedposition. When it is recalled that the construction at each end of thetubular switch member 19 is identical and that ordinarily three poles ofa construction similar to that shown in Figure l are employed and allthree are operated simultaneously, the advantage of such an arrangementis obvious.

While the convex contact surfaces 44 are shown and 7 described as beinglocated on the contact fingers 40 for engagement with flat contactsurfaces on the inserts 26, it will be understood that the flat surfacescan be transposed to the contact fingers 40 and the convex surfaces tothe inserts 26.

Referring now particularly to Figures 11, 12 and 13 of the drawings, itwill be observed that the reference character 71 designates, generally,a disconnecting switch of the knife blade type which is provided withinsulators 72 having metal caps 73 at their upper ends. Any suitablebase can be provided for supporting the insulators 72 and it will beunderstood that the switch 71 can be located in various positions as maybe required; Secured by bolts 74 and 75 to the caps 73 are base m mbers76 and 77 from which terminal pads 78 and 79 extend to permit connectionof line conductors thereto.

The base member 76 is provided witha pair of up standing hinge members80 to which at 81 are pivoted the bifurcated ends of a switch blade thatis shown, generally, at 82. A pull ring 83 is secured to the switchblade 82 near its swinging end for receiving the prong of a switch stickto permit opening and closing of the switch blade 82. It will beunderstood that the switch blade 82 can be swung through 90 to theposition shown by the broken lines or through 180 if desired.Conventional locking mechanism can be employed for holding the switchblade 82 in the switch closed position. Also suitable stops can beprovided for limiting the opening movement thereof. Since these featuresform no part of the present invention, they are not illustrated ordescribed.

Mounted on the base member 77 for engagement by the swinging end of theswitch blade 82 is a contact assembly that is shown, generally, at 84.The contact assembly 84 includes a pair of spaced apart upstanding arms85 that are substantially of rectangular cross section and arerelatively rigid. They are formed preferably integrally with the basemember 77.

Secured to the upstanding arms 85 by rivets 86 are outer branches 87 offlexible resilient U-shaped conductors that are indicated, generally, at88. It will be noted that a pair of U-shaped conductors 88 is employed,one U-shaped conductor 88 being mounted on each of the upstanding arms85. Inner branches 89 of the U-shaped conductors 88 are longitudinallyslotted at their ends as indicated at 90 to provide a bifurcated endportion through which rivets 91 extend for securing contact fingers 92thereto. The contact fingers 92 have convex contact surfaces 93 thatextend transversely of the inner branches 89 of the U-shaped conductors88 rather than longitudinally thereof as is the case for the convexcontact surfaces 44 of the contact fingers 40 which are shown moreclearly in Figures 8 of the drawings. The reason for the transversepositioning of the convex con tact surfaces 93 for contact engagementwith inserts 94 in an end portion 95 of the switch blade 82 therebetweenis to provide for receiving this end portion 95 as it swings in thedirection indicated by the double headed arrow 96 into and out ofengagement with the contact assembly 84. Here the end portion 95 of theswitch blade 82 engages the contact assembly 84 sidewise rather thanendwise as is the case in the switch construction illustrated in Figures1-10 of the drawings. Except for the transverse positioning of theconvex contact surfaces 93, they are of the proportions describedhereinbeforc for the convex contact surfaces 44 of the contact fingers40.

In order to urge the convex contact surfaces 93 into high pressurecontact engagement with the inserts 94 in the end portion 95 of theswitch blade 82 leaf springs 97 are employed. One end 98 of each leafspring 97 is turned inwardly and bear against the rear side of therespective contact finger 92. The other end 99 of each leaf spring 97bears against the respective end 100 of a loading pin 101 which extendsbetween the inner branches 89 and is located adjacent the bottomof theU-shaped 8 conductors central portion of the loading pin 101 is"enlarged and is provided with shoulders 102 at the ends which bearagainst the facing surfaces of the inner branches '89 in the absence ofthe end portion 95 of the switch blade. In part this construction limitsthe movement or the contact fingers 92 toward each other to provide aprestresscd arran ement for the leaf springs 97.

It is desirable to mechanically interconnect the ushaped conductors 88in order to distribute stress therebetween. For this purposeintermediate portions 103 of the leaf springs 97 are engaged by loadingpins 104 which extend transversely through an equalizer bar 105. Theequalizer bar 105 is located in a position parallel to the loading in101 and extendsthrough the slots in the inner branches 89 and its endsproject through suitable clearance openings lathe outer branches s7 tolimit the lateral deflection ofths inner branches 89 when the endportion ofthe switch blade 82' enters the Contact assembly 84.

With a View to further limiting the movement of the inner branches 89'towardeachother under the influence of the leaf springs 97 when theswitch blade 82 is out of engagement with the contact assembly 84, aspacer sleeve 106 is telescoped over the central portion of theequalizerbar 105. The ends of the spacer sleeve 106 and the shoulders102 of :the loading pin 101 are spaced apart such that the convexcontact surfaces 93 are permitted to move toward each other to adistance apart slightly past the locations of the respective contactsurface of the inserts 94 when the end portion 95 of the switch blade 82is in the switch closed position. This provides a prestressedconstruction which requires only 'a small amount of movement apart ofthe contact fingers 92 when the switch blade 82is closed in order todevelop the full springpressure of theleaf springs 97.

The spacer sleeve 106 can be held in position against endwisefmovementon the equalizer bar by transversely extending :pin 10.7. A slottedguidel08 extends upwardlyfro'm the space member 77 and is provided withbeveled edges 109 for guiding the end portion 95 of the switch blade '82into the contact assembly 84.

Figure 14 shows a contact assembly that is indicated, generally, at .111which can be employed in lieu of the contact assembly 824 which ,isshown in Figures 11-13. The contact assembly 111 has a base member 112which corresponds to the base member 77. It, is provided with theslottedv guide 108 previously described. ,At the other end the :basemember 112 has an integrally formed upstanding wall .113 from whicharm's 114 laterally extend. The arms 114 correspond to the upstandingarms 85 of the contact assembly 84. To the outer ends of the laterallyextending arms 114 the flexible resilient U- shaped conductors 8,8 aresecured by rivets 86 as de scribed previously.

It is desirable that the tendency for the switch blade 82 to move or tobe thrown open as the result of magnetic forces generated by flow ofcurrent be minimized. Even when the switch blade 82 is latched in theclosed position, it is desirable that it remain stationary. When it isrecalled thatthese magnetic forces may become relatively great .on flowof heavy current, such as the fiow of short circuit current involvingmany thousands of amperes, it will be appreciated that provision shouldbe made either for minimizing the effect of these forces or formechanically locking the switch blade 82in the switch closed position.In accordance with this invention provision is made for minimizing theeffect of the magnetic forces by providing a terminal pad 115intermediate the upper and lower edges of the upstanding wall 113 andgenerally in line with the switch blade 82 or end portion 95 thereofwhen "it occupies the switch closed position. By connecting the lineconductor to the terminal pad 115 located as illustrated inFigur'e 14,aninline relationship with the switch blade 82 is established and'themagnetic forces incident to the flow of heavy current, such as shortcircuit current, do not tend to swing theswitch blade to the openposition.

Figures 15 and 16 show, generally, at 117 a contact assembly which canbe employed where the normal flow of load current exceeds that for theswitch construction 71, for example, shown in Figures 11-13 of thedrawings. In Figures 15-l6 a switch blade 82 is employed which isgenerally of the same construction as the switch blade 82, previouslydescribed, but is wider. It is provided with a pull ring 83. The switchblade 82 has an end portion 95' which is arranged to engage convexcontact surfaces 93 of contact fingers 92 which are carried by flexibleresilient U-shaped conductors 88, as previously described. However, intheconstruction here illustrated two pairs of U-shaped conductors 88 areemployed in order to give increased current canrying capacity.

The contact assembly 117 includes a base member 118 which is providedwith a slotted guide 119 on one side that corresponds to the slottedguide 108 previously described. n the other side the base member 118 hasan integrally formed upstanding wall 120 which is provided withlaterally extending arms 121 on which the U-shaped conductors 88 aremounted in the manner described for Figure 14. A terminal pad 122extends laterally from the upstanding wall 120 and is located generallyin line with the end portion 95' of the switch blade 82 when it is inthe switch closed position. As previously described, this arrangementminimizes the effects of the magnetic forces incident to the flow ofheavy current,

such as short circuit current, in acting to swing the switch blade tothe open position.

Referring to Figure 15 of the drawings, it will be observed that adouble loop effect is provided with respect to the flow of current inthe contact assembly 117. Here it will be observed that the currentflows from the terminal pad 122 as indicated by the arrows 123 to thelaterally extending arms 121. Then, as indicated by the arrows 124, thecurrent flows in a reverse direction through the outer branches 87 ofthe U-shaped conductors 88. Finally the current flows to the contactfingers through the inner branches 89 as indicated by the arrows 125.The relationship of the magnetic fields thus generated is such as tourge the contact fingers 92 into engagement with the opposite sides ofthe end portion 95' of the switch blade 82 with even greater force andcertainty than if this double loop construction is not employed,particularly if the loading pin 101 is not used. Thus, the contactpressure with the switch blade is increased, particularly under shortcircuit conditions, in proportion to the flow of current. The samerelationship holds for the contact assembly 111 shown in Figure 14.

Figures 17 and 18 of the drawings show a switch construction which, incertain respects, is the reverse of that illustrated in the precedingfigures. Here a switch blade is provided and is indicated generally at127. The switch blade 127 can be pivoted in the manner describedhereinbefore for the switch blade 82. A shown in Figures 17 and 18 theswitch blade 127 comprises spaced-apart blade members 128 which areinterconnected by spacer pins 129. The blade members 128 are arranged tostraddle a contact assembly that is indicated, generally, at 130.

On the inner sides of the blade members 128 inserts 131 are provided forhigh pressure contact engagement with convex contact surfaces 132 whichextend lengthwise of contact fingers 133. Generally the contact fingers133 are constructed in a manner described hereinbefore for the contactfingers 40. The contact fingers 133 are secured by rivets 134 to outerbifurcated branches 135 of flexible resilient U-shaped conductors thatare indicated, generally, at 136. The U-shaped conductors 136 have innerbranches 137 which are secured by rivets 138 to opposite sides of anupper thicker portion 139 of an arm 140 that extends upwardly from abase member 141. It will be understood that the base member 141 can beseflared by b01ts142 to .a suitable insulator cap, correspondit? ing tothe cap 73 previously described. Extending laterally from the basemember 141 is a terminal pad 143 for receiving a line conductor.

In order to bias the convex contact surfaces 32 outwardly into highpressure contact engagement with the inserts 131 on the inner faces ofthe blade members 128, one end 146 of each of a pair of leaf springs 147bears against the rear side of the respective contact finger 133. Theother ends 148 of the leaf springs 146 bear against the lower portionsof the outer branches of the U-shaped conductors 136. Thus the leafsprings 147 overlie the outer branches 135 and are spaced slightlytherefrom. The intermediate portions of the leaf springs 147 are engagedby loading pins 149 that extend transversely through an equalizer bar150. It will be noted that the equalizer bar 150 extends through the arm140, the inner branches 137 of the U-shaped conductors 136 and throughthe slotted openings in the bifurcated outer branches 135. At one end ofthe equalizer bar 150 there is a head 151 and a nut 152 is threaded onthe other end. It will be understood that the equalizer bar 150 isloaded in compression against the loading pins 149 when the blademembers 128 are in the switch closed position shown 'in Figure 18.'Ihe'pressures applied by the leaf springs 147 to the contact fingers133 are equalized since the equalizer bar 150 is free to shiftlongitudinally except as restrained by the loading pins 149 inengagement with the leaf springs 147. The head 151 and nut 152 limit theoutward movement of the contact fingers 133 when the switch blade 127 isopen to position the convex contact surfaces 132 at locations slightlypast the respective contact surface of the inserts 131 when they are inthe switch closed position and to prestress the leaf springs 147.

It will be observed that the arm 140 has a lower thinner portion 153which is spaced from the facing sides of the inner branches 137. Thisaffords some degree of flexibility to the U-shaped conductors 136 andpermits advantage to be taken of the double loop efiect previouslydescribed in connection with Figure 15.

Extending through the lower thinner portion 153 of the arm 140 andthrough the inner branches near the base of the U-shape there is aloading pin 154 which is provided with heads 155 at the ends in the formof stop rings that are suitably secured in position. The heads or stoprings 155 have shoulders 156 which engage the outer sides of the innerbranches 137. This construction limits the movement apart ofthe innerbranches 137 and thus assists in the preloading of the contact fingers133 by the leaf springs 147. This construction serves to mechanicallyinterconnect the U-shaped conductors 136 and eifects conjoint movementthereof should the blade member 128 be slightly out of alignment withthe contact assembly 130. Some clearance, as indicated at 157, isprovided between shoulders 158 on the loading pin 154 and the innerfaces of the inner branches 137. This permits some articulation in theinterconnection between the U-shaped conductors 136. The inner branches137 would tend to move inwardly as a result of the magnetic forces setup between them and the outer branches 135 but this tendency is opposedby the magnetic forces resulting from current flowing through the innerbranches 137 and the portion 153 of the arm 140 thereby providing thedouble loop effect referred to above.

Since the current fiow in the outer branches 135 is opposite to thedirection of current flow through the inner branches 137, the magneticforces generated thereby tend to cause these, branches to move away fromeach other. Since the inner branches 137 are rigidly secured to theupper tlhicker portion 139 of the arm 140 the net result of thisconstruction is to increase the contact pressure exerted against theblade member 128. Thus on flow of high current, such as short circuitcurrent, there is increase in the contact pressure applied to the blademembers 128. Under these circumstances the outer branches 135 tend toswing outwardly about the shoulders 158 as fulcrums. I I

It'will be understood that suitable stops are provided for limiting themovement of the blade members 128 to the positions shown in Figure'18.Also, suitable latch mechanism is provided to prevent the blade members128 from moving to the open position on flow of relatively heavycurrent, such as short circuit current.

Figure 19 shows a contact assembly 130 which is generally the reverse ofthe construction for the contact assembly 130. Here the blade members128 are arranged to approach closer to the base member 141. To limit themovement of the blade members 128 stop bosses 161 can be formedintegrally with the base member 141. In this construction an arm 162,corresponding to the arm 140, is carried by the base member 141.However, it has a lower thicker portion 163 to which the inner branches137 of the U-shaped conductors 136 are secured by the rivets 138.It'will be observed that the U-s'haped conductors 136 have the U-shapeopening in the direction of closing movement of the blade members 128 incontradistinction to the construction shown in Figure 18 where theopenings of, the U-shaped conductors 136 are in the direction of openingmovement of the blade members 128. The arm 162 has an upper thinnerportion 164 to permit a greater degree of flexibility for the U-shapedconductors 136 in the manner described hereinbefore.

The magnetic fields generated on flow of current through the switchconstruction illustrated in Figure 19 are such as to tend to causethe'switch blade 127 to move toward the switch closed position or tohold it in the closed position. This is particularly true on flow ofheavy current or short circuit current. In addition, on flow of suchcurrent, the reaction is such as to increase the contact pressureapplied to theblad'e members 128.

Referring now particularly to Figures 20-22 of the drawings, a contactassembly or'line contact member is shown, generally, at 170, which isparticularly adapted for use with a disconnecting switch of the beavertail type such as that disclosed in copending application Serial No.704,397, filed December 23, 1957. Since the hinge end of the switchmechanism forms no part of the present invention, only a portion oftheswiteh'blade 171 is shown herein. It will be understood that the switchblade 171 is arranged to .be swung about'an axis transverse to itslongitudinal axis and also thatit is arranged to be rotated about itslongitudinal axis to move laterally extending ears 172 into highpressure contact engagement with contact surfaces that may be providedby silver inlays 173 that are mounted on the inner sides of downturnedbifurcated inner branches 174 offlexible'resilient inverted U-shapedconductors that are shown, generally, at 175. The U- shaped conductors175 include downturned outer branches 176 which are secured by bolts 177to a contact housing 178. Extending upwardly along opposite sides of theouter branches 176 are arms 179 that may be formed integrally with thehousing 178 and have transverse webs 180 normally in spaced relation tothe outer sides of the outer branches 176. Transverse pins 181 at theupper ends of the arms 1'19 limit themovement of the outer branches 176.toward each other. The .contact housing 178 extends upwardly from acontact base 182 that is suitably mounted on an insulator and isprovided with a line terminal pad all as described in the applicationlast referred to.

With a view to urg'ingthe contact surfaces provided by the silver inlays173 on the downturned inner branches 174 into good contact engagementwith the outer edges of the ears 172 upper bifurcated ends 183 of leafsprings 184 bear against the outer sides of the inner branches 17 4generally in alignment with'the ears 172 in the switch closed position.The lower bifurcated ends 185 of the leaf springs 184 bearagainst thelower ends of the inner branches 174 and are centered on projecting ends186 of a loading pin 187 which extends between the lower ends of theinner branches 174 as shown. Central portions 1'2 188 of the leafsprings 184 bear against the outer branches 176.

The contact pressures applied by the leaf springs 184 are equalized byan equalizer bar 189 which extends through the slots in the bifurcatedinner branches 174'and through the central portions 188 of the leafsprings 184 and project beyond the outer branches 176 where loading pins190 serve to interconnect mechanically these outer branches 176.

It is desirable to space the contact surfaces of the silver inlays 173apart in the absence of the ears 172 and for this purpose a spacersleeve 191 is telescoped over the central portion of the equalizer bar189 and is secured thereto by a pin 192. The central portion of theloading pin 187 and the spacer sleeve 191'serve to space the innerbranches 174 apart the desired distance in the absence of the switchblade 171 and to preload the leaf springs 184.

The movement of the switch blade 171 toward the switch closed positionis limited by a stop pin 193 which is carried by the contact housing 178and extends upwardly from the lower portion thereof.

The construction of the contact assembly or line contact member is suchas to accommodate some misalignment between the switch blade 171 and thecontact assembly 170. Also, as described, it provides for equalizing thecontact pressure that is applied to the ears 172 on the switch blade171. During heavy current flow, such as under short circuit conditions,the contact pressure between the ears 172 on the switch blade 171 andthe inner branches 174 increases greatly because of the forces developedas a result of the U-shape of the conductors 175. Under these conditionsthe inner branches 174 tend to move away from the outer branches 176which are mechanically interconnected by the equalizer bar 189.Ultimately the outer branches 176 engage the transverse webs resultingin maximum pressure being exerted by the inner branches 174 through thesilver inlays 173 against the outer edges of the ears 172. The forceexerted against these ears is not changed by distortion of the innerbranches 174.

At its swinging end the switch blade 171 is provided with an arcing tip194 that is arranged to provide the initial and final contact engagementbetween the switch blade 171 and the contact assembly 170. The arcingtip 194 constitutes an endwise extension of the switch blade 171 and itcan be readily removed and replaced should it become eroded due toarcing. It is arranged to engage and disengage flexible arcing horns 195and 196 having circular cross sections which are secured in staggeredrelation by set screws 197 to the contact base 182 of the contacthousing 178. The arcing horns 195 and 196 are spaced apart along thearcing tip 194 in the switch closed position for a distance severaltimes the transverse dimension or diameter of the arcing horns 195 and196. The reasons for positioning the arcing horns 195 and 196 instaggered relation are to facilitate the breaking of ice should theybecome so encased under certain adverse weather conditions and to insurethat contact is always maintained on one side or the other of the arcingtip 194 despite strong lateral vibrations of the arcing horns 195 and196 and the switch blade 171 incident to fast operation. and 196 arelikely to require replacement, they are de tachably mounted, asindicated, on the contact base 182 by the set screws 197.

Figures 23 and 24 show, generally, at 200 a contact assembly which canbe employed in lieu of the contact The' contact assembly 200 is arrangedfor cooperation with assembly shown in Figures 20-22 of the drawings.

the switch blade 171 that is operated as described hereinbefore andincludes a contact base 201 that can be mounted on a suitable insulator.The contact base 201 is provided with a terminal pad 202 for connectionto a Since the arcing horns 195 with the arcing tip 194, previouslyreferred to, for engagement with an arcing horn 195 that extendsupwardly from the contact base 201.

The upper portion of the contact base 201 is formed by a contact housing203 which has arms 204 that extend outwardly and upwardly. To theintermediate portions of the arms 204 bolts 205 secure outer branches206 of flexible resilient U-shaped conductors that are shown, generally,at 207. These U-shaped conductors 207 have inner branches 2% which carrycontact fingers 209 at their upper ends. Rivets 210 secure the contactfingers 209 to the upper ends of the inner branches 208. It will benoted that the facing sides of the contact fingers 209 have elongatedconvex contact surfaces 211 for high pressure contact engagement withthe ears 172 that extend laterally from the switch blade 171.

The contact fingers 209 are urged into high pressure contact engagementwith the ears 172 by the upper ends 212 of leaf springs 213 the lowerends 214 of which bear against outer ends 215 of a loading pin 216 whichextends between the inner branches 208 at the base portions of theU-shape.

It is desirable to provide for distributing the contact pressure appliedby the leaf springs 213. For this purpose loading pins 217 bear againstthe central portions of the leaf springs 213 and extend transverselythrough an equalizer bar 218. It will be understood that the equalizerbar 218 extends through the inner branches 208 which are bifurcated andalso through the leaf springs 213. Surrounding the equalizer bar 218 isa spacer sleeve 219. It, together with the loading pin 216, limits themovement of the contact fingers 209 toward each other under theinfluence of the leaf springs 213 in the absence of the switch blade 171or more particularly when the ears 172 are not in engagement with theelongated convex contact surfaces 211.

As a further means for limiting the movement of the contact fingers 209toward each other in the absence of the switch blade 1'71, stops 220depend from the upper ends of the arms 204 into the paths of the upperends 221 of the contact fingers 209. When the switch blade 171 is in theopen position, the stops 220 are engaged by the upper ends 221 of thecontact fingers 209 while the inner surfaces of the inner branches 208bear against the ends of the loading pin 216 and the spacer sleeve 219.

It will be understood that the current flow through the arms 204- andU-shaped conductors 207 is generally of the character describedhereinbefore for the contact assembly 117 shown in Figure 15. That is,there is a reverse loop effect since the current flows upwardly throughthe arms 204, then downwardly through the outer branches 206 and finallyupwardly through the inner branches 208 to the switch blade 171.Increased contact pressure results from this arrangement in the mannerpreviously described.

The movement of the switch blade 171 to the switch closed position islimited by a stop pin 224 which is carried by the contact housing 203and extends upwardly therefrom.

Since certain further modifications and arrangements of the inventioncan be made without departing from the spirit and scope thereof, it isintended that all matters shown in the accompanying drawings anddescribed hereinbefore shall be interpreted as illustrative and not in alimiting sense.

What is claimed as new is:

1. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other with contact meansextending lengthwise thereof at their outer ends for engaging oppositesides of said switch blade therebetween, means baising said contactmeans 14 into high pressure contact engagement with said switch blade,and means limiting the movement of said contact means toward each otherto a distance apart slightly less than the distance between the oppositesides of said switch blade engaged by said contact means in switchclosed position.

2. In a switch, in combination, a switch blade and arelatively movablecontact assembly mounted in insulatedspaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other with contact meansextending lengthwise thereof at their outer ends for engaging oppositesides of said switch blade therebetween, each contact means having aconvex con: tact surface with the radius of the longitudinal portionbeing substantially greater than the radius of the transverse portion,means biasing said contact means into high pressure contact engagementwith said switch blade, and means limiting the movement of said contactmeans toward each other to a distance apart slightly less than thedistance between the opposite sides of said switch blade engaged by saidcontact means in switch closed position.

3. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced. relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving their outer branches rigidly supported in spaced relation andtheir inner branches facing each other and split lengthwise to provideindependently movable legs, a relatively massive contact finger carriedby the outer end of each leg having a convex contact surface for smallarea contact engagement with opposite sides of said switch blade, thelengths of the current paths in said branches of said U-shaped conductorbeing substantially equal whereby the resulting magnetic forces actingto increase the contact pressure applied by said contact fingers to saidswitch blade attain a maximum for any given current flow therethrough,means individually biasing said contact fingers into high pressurecontact engagement with said switch blade, and means limiting themovement of said contact fingers toward each other to a distance apartslightly less than the distance between the opposite sides of saidswitch blade engaged thereby in switch closed posit1on.

4. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving their outer branches rigidly supported in spaced relation andtheir inner branches facing each other and split lengthwise to provideindependently movable legs, a relatively massive contact finger carriedby the outer end of each leg having a convex contact surface with theradius of the longitudinal portion being substantially greater than theradius of the transverse portion for small area contact engagement withopposite sides of said switch blade, the lengths of the current paths insaid branches of said U-shaped conductors being substantially equalwhereby the resulting magnetic forces act to increase the contactpressure applied by said contact fingers to said switch blade inproportion to the current flow therethrough, means individually biasingsaid contact fingers into high pressure contact engagement with saidswitch blade, and means limiting the movement of said contact fingerstoward each other to a distance apart slightly less than the distancebetween the opposite sides of said switch blade engaged thereby inswitch closed position.

5. A switch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a pair of spaced relatively inflexiblecontact support arms, a pair of relatively flexible resilient U-shapedconductors extending from said contact support arms and having the outerbranches overlying and secured to said arms and the inner branchesextending between and spaced from the inner sides of said arms and fromeach other, relatively massive contact finger means secured to the outerend of each of said inner branches and extending lengthwise thereof andproviding on their facing sides contact surfaces engaging the oppositesides of said switch blade, a spacer intermediate the facing sides ofsaid inner branches and holding the opposite contact surfaces of saidcontact finger means apart in the switch open posi tion a distanceslightly less than the thickness of said switch blade where they areengaged thereby in the switch closed position, an equalizer barextending through said inner branches with its ends projecting eyond theouter side'sthercof and retaining means at each end, and a spring leafoverlying the outer sides of said inner branches with the inner endsreacting against the same, the intermediate portions of said springleaves being located between the respective retaining means on saidequalizer bar and said outer sides of said inner branches and reactingagainst the former, and the outer ends of said spring leaves reactingagainst the rear sides of the respective contact finger means.

6. A switch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a pair of spaced relatively inflexiblecontact support arms, a pair of relatively flexible resilient U-shapedconductors extending from said contact support arms and having the outerbranches extending between and spaced from the inner sides of said armsand from each other with relatively massive contact means secured to theouter end of each of said inner branches and extending lengthwisethereof and providing on their facing sides contact surfaces engagingthe opposite sides of said switch blade, a spacer sleeve intermediatethe facing sides of said inner branches and holding the opposite contactsurfaces of said contact finger means apart in the switch open positiona distance slightly less than the thickness of said switch blade wherethey are engaged thereby in the switch closed position, an equalizer barextending through said spacer sleeve with its ends projecting beyond theouter sides of said inner branches and retaining means at each end, aloading pin extending between said inner branches near their inner endsand having reduced end portions projecting beyond said outer sidesthereof, and a spring leaf overlying the outer sides of said innerbranches with its inner end portion guided by the respective end portionof said loading pin and reacting against said outer sides of said innerbranches, the intermediate portions of said spring leaves being locatedbetween the respective retaining means on said equalizer bar and saidouter sides of said inner branches and reacting against the former, andthe outer ends of said spring leaves reacting against the rear sides ofthe respective contact finger means.

7. A switch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a'pair of spaced relatively inflexiblecontact support arms, a pair of relatively flexible resilient U-shapedconductors extending from said contact support arms and having the outerbranches overlying and secured to said arms and the inner branchesextending between and spaced from the inner sides of said arms and fromeach other, relatively massive contact finger means secured to the outerend of each of said inner branches and extending lengthwise thereof andproviding on their facing sides contact surfaces engaging the oppositesides of said switch blade, each contact surface being convex with theradius of the longitudinal contact surface being substantially greaterthan the radius of the transverse contact surface, a spacer sleeveintermediate the facing sides of said inner branches and holding theopposite contact surfaces of said contact finger means apart in theswitch open position a distance slightly less than the thickness of saidswitch blade where they are engaged thereby in the switch closedposition, an equalizer bar extending through said spacer sleeve with itsends projecting beyond the outer sides of said inner branches andretaining means at each end, "a loading pin extending between said innerbranches near their inner ends and having reduced end portionsprojecting beyond said outer sides thereof, and a spring leaf overlyingthe outer sides of said inner branches with its inner end portion guidedby the respective end portion of said loading pin and reacting againstsaid outer sides of said inner branches, the in termediate portions ofsaid spring leaves being located between the respective retaining meanson said equalizer bar and said outer sides of said inner branches andreacting against the former, and the outer ends of said spring leaveshaving limited area high pressure contact engagement with the rear sidesof the respective contact finger means centrally of the respectivecontact surface.

8. Aswitch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a U-shaped relatively inflexible contactsupport, a pair of relatively flexible resilient U-shaped conductorsextending from the arms of said contact support and having the outerbranches secured to said arms and the inner branches split lengthwiseand extending between and spaced from said arms and from each other, arelatively massive contact finger secured to the outer end of each ofthe legs of said inner branches and extending lengthwise thereof andtherewith having limited movement relative to each other and providingon their front sides contact surfaces engaging the opposite sides ofsaid switch blade, a spacer intermediate the facing sides of said innerbranches and holding the opposite contact surfaces of said contactfingers apart in the switch open position a distance slightly less thanthe thickness of said switch blade where they are engaged thereby in theswitch closed position, an equalizer bar extending through said innerbranches with its ends projecting beyond the outer sides thereof and apin extending transversely through each end, and a spring leaf overlyingthe outer sides of said inner branches with the inner ends reactingagainst said outer sides of said inner branches, the intermediateportions of said spring leaves being located between the respectivetransverse pins in said equalizer bar and said outer sides of said innerbranches and reacting against the former, the outer ends of said springleaves being bifurcated and reacting against the rear sides of therespective contact fingers.

9. A switch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a U-shaped relatively inflexible contactsupport, a pair of relatively flexible resilient U-shaped conductorsextending laterally of the arms of said contact support and having theouter branches secured to said arms and the inner branches splitlengthwise and extending between and spaced from said arms and from eachother, a relatively massive contact finger secured to the outer end ofeach of the legs of said inner branches and extending lengthwise thereofand therewith having limited movement relative to each other andproviding on their front sides contact surfaces engaging the oppositesides of said switch blade, each contact surface being convex with theradius of the longitudinal contact surface being substantially greaterthan the radius of the transverse contact surface, a spacer intermediatethe facing sides of said inner branches and holding the opposite contactsurfaces of said contact fingers apart in the switch open position adistance slightly less than the thickness of said switchblade where theyare engaged thereby in the switch closed position, an equalizer barextending through said inner branches with its ends projecting beyondthe outer sides thereof and a pin extending transversely through eachend, and a spring leaf overlying the outer sides of said inner brancheswith the inner ends reacting against said outer sides of said innerbranches, the intermediate portions of said spring leaves being locatedbetween the respective transverse pins in said equalizer bar and saidouter sides of said inner branches and reacting against the former, theouter ends of said spring leaves being bifurcated and having limitedarea high pressure contact engagement with the rear sides of therespective contact fingers centrally of the respective contact surface.

10. A switch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a U-shaped relatively inflexible contactsupport, a pair of relatively flexible resilient U-shaped conductorsextending laterally of the arms of said contact support and having theouter branches secured to said arms and the inner branches splitlengthwise and extending between and spaced from said arms and from eachother, a relatively massive contact finger secured to the outer end ofeach of the legs of said inner branches and extending lengthwise thereofand therewith having limited movement relative to each other andproviding on their front sides contact surfaces engaging the oppositesides of said switch blade, each contact surface being convex with theradius of the longitudinal contact surface being substantially greaterthan the radius of the transverse contact surface, a spacer sleeveintermediate the facing sides of said inner branches and holding theopposite contact surfaces of said contact fingers apart in the switchopen position a distance slightly less than the thickness of said switchblade where they are engaged thereby in the switch closed position, anequalizer bar extending through said spacer sleeve with its endsprojecting beyond the outer sides of said inner branches and a pinextending transversely through each end, and a spring leaf overlying theouter sides of said inner branches with the inner ends reacting againstsaid outer sides of said inner branches, the intermediate portions ofsaid spring leaves being located between the respective transverse pinsin said equalizer bar and said outer sides of said inner branches andreacting against the former, the outer ends of said spring leaves beingbifurcated and having limited area high pressure contact engagement withthe rear sides of the respective contact fingers centrally of therespective contact surface.

11. A switch comprising, in combination, a switch blade and a relativelymovable contact assembly mounted in insulated spaced relation, saidcontact assembly including a U-shaped relatively inflexible contactsupport, a pair of relatively flexible resilient U-shaped conductorsextending laterally of the arms of said contact support and having theouter branches secured to said arms and the inner branches splitlengthwise and extending between and spaced from said arms and from eachother, a relatively massive contact finger secured to the outer end ofeach of the legs of said inner branches and extending lengthwise thereofand therewith having limited movement relative to each other andproviding on their front sides contact surfaces engaging the oppositesides of said switch blade, each contact surface being convex with theradius of the longitudinal contact surface being substantially greaterthan the radius of the transverse contact surface, a spacer sleeveintermediate the facing sides of said inner branches and holding theopposite contact surfaces of said contact fingers apart in the switchopen position a distance slightly less than the thickness of said switchblade where they are engaged thereby in the switch closed position, anequalizer bar extending through said spacer sleeve with its endsprojecting beyond the outer sides of said inner branches and a pinextending transversely through each end, a loading pin extending betweensaid inner branches at the base of the split in each and having reducedend portions projecting beyond said outer sides thereof, and a springleaf at each end of said loading pin with its end portions guiding therespective inner ends of the spring leaves and the same bearing againstspacing means reacting against said outer sides of said inner branches,the intermediate portions of said spring leaves being located betweenthe respective transverse pins in said equalizer bar and said outersides of said inner branches and bearing against the former, the outerends of said spring leaves being bifurcated and having limited area highpressure contact engagement with the rear sides of the respectivecontact fingers centrally of the respective contact surface.

12. A switch comprising, in combination, a switch blade and a relativelyendwise movable contact assembly mounted in insulated spaced relation,said contact assembly including a U-shaped relatively inflexible contactsupport with a central mounting ear extending laterally away from saidswitch blade in closed position, a pair of relatively flexible resilientU-shaped conductors parallel to said ear having the outer branchesoverlying and secured to the outer sides of the arms of said contactsupport and the inner branches split lengthwise and extending betweenand spaced from the inner sides of said arms and from each other withtheir ends spaced from the lateral edges of said arms away from saidear, a relatively massive contact finger secured to the inner facingside of each of the legs of said inner branches and extending to saidlateral edges of said arms and having limited movement relative to eachother and providing on their front sides contact surfaces engaging theoppo site sides of said switch blade, each contact surface being convexwith the radius of the longitudinal contact surface being substantiallygreater than the radius of the transverse contact surface, a spacersleeve intermediate the facing sides of said inner branches and holdingthe,

opposite contact surfaces of said contact fingers apart in the switchopen position a distance slightly less than the thickness of said switchblade where they are engaged thereby in the switch closed position, anequalizer bar extending through said spacer sleeve with its endsprojecting beyond the outer sides of said inner branches and a pinextending transversely through each end, a loading pin extending betweensaid inner branches at the base of the split in each and having reducedend por-- tions projecting beyond said outer sides thereof, a collar oneach of said end portions bearing against the outer side of therespective inner branch and having a convex outer end surface, and aspring leaf at each end of said loading pin with its end portionsguiding the respective ends of the spring leaves and the same bearingagainst the respective convex end surface of each collar, theintermediate portions of said spring leaves being located between therespective transverse pins in said equalizer bar and said outer sides ofsaid inner branches and bearing against the former, the other ends ofsaid spring leaves being bifurcated and turned inwardly to overlie therespective ends of said legs of said inner branches and having limitedarea high pressure contact engagement with the rear sides of therespective contact fingers centrally of the respective contact surface.

13. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other with contact meansextending lengthwise thereof at their outer ends for engaging oppositesides of said switch blade therebetween, means biasing said contactmeans into high pressure contact engagement with said switch blade,articulated interconnecting means between said inner branches fordistributing substantially equally the contact pressure applied by saidcontact means to said opposite sides of said switch blade, and means foreffecting relative movement between said switch blade and contactassembly such that the former enters and 19 leaves the latter at saidouter ends of said inner branches.

14, In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of Ushaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other with contact meansextending lengthwise thereof at their outer ends for engaging oppositesides of said switch blade therebetween, means biasing said contactmeans into high pressure contact engagement with said switch blade,means limiting the movement of said contact means toward each other to adistance apart slightly less than the distance between the oppositesides of said switch blade engaged by said contact means in switchclosed position, and means for effecting relative movement between saidswitch blade and contact assembly such that the former enters and leavesthe latter at said outer ends of said inner branches.

15. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, means biasingsaid contact means into high pressure contact engagement with saidcontact surfaces of said switch blade, and an equalizer bar mechanicallyinterconnecting said U- shaped conductors to distribute the contactpressures applied by said biasing means through said contact means tosaid contact surfaces.

16; In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact asernbly including a pair of U sha'pedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, means biasingsaid contact means into high pressure contact engagement with saidcontact surfaces of said switch blade, means limiting the movement ofsaid contact means toward said contact surfaces to a distance slightlypast the respective contact surface of said switch blade engaged by saidcontact means in switch closed position, and an equalizer barmechanically interconnecting said U-shaped conductors to distribute thecontact pressures applied by said biasing rrieans through said contactmeans to said contact surfaces.

17. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, meansindividual to each contact means biasing the same into high pressurecontact engagement with said contact surfaces of said switch blade, andan equalizer bar extending past adjacent branches of said U-shapedconductors and mechanically interconnecting said biasing means todistribute the contact pressures applied by said biasing means throughsaid contact means to said contact surfaces.

18. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U'-shapedil'eii-ilale resili'ent conductors having the ends cf a branch of eachrigidly supported in spaced relation and their other branchesfacing saidcontact surfaces of said switch blade, means limiting the movement ofsaid contact means toward said contact surfaces to a distance slightlypast the re spect-ive contact surface of said switch blade engaged bysaid contact means in switch closed position with contact means thereonfor engaging said contact surfaces of said switch blade, meansindividual to each contact means biasing the same into high pressurecontact engagement with said contact surfaces of said switch blade, andan equalizer bar extending past adjacent branches of said U-shapedconductors and mechanically interconnecting said biasing means todistribute the contact pressures applied by said biasing means throughsaid contact means to said co'ntact surfaces.

19. In a switch, in combination,- a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of Ushapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, means biasingsaid contact means into high pressure contact engagement with saidcontact surfaces of said switch blade, an equalizer b'ar extending pastadjacent branches of said U-shaped conductors andmechanicallyinterconnecting said U-shaped conductors to distribute thecontact pressures applied by said biasing means through said contactmeans to said contact surfaces, and a loading pin extending between saidadjacent branches in spaced relation to said equalizer bar.

20. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapcdflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contactsurfaces of said switch blade with contact means thereon forengaging said contact surfaces of said switch blade, means biasing saidcontact meansinto high pressure contact engagement with said contactsiirfaces of said switch blade, means limiting the rricveihent of saidcontact means toward said contact surfaces to a distance slightly pastthe respective contact surface (if said switch blade engaged by saidcontact means in switch closed position, an equalizer bar extending pastadjacent branches of said U-shaped conductors and mechanicallyinterconnecting said U-shaped conductors to distribute thecemaeipressures applied by said biasing means through said contact means tosaid contact surraces, and a leading pin extending between said adjacentbranches in spaced relation to said equalizer bar.

21. In a "switch, in combination, a switch blade having spacedccntactsiirfac'es and a relatively movable contact assembly nioiinted ininsulated spaced relation, said contact assembly including a pair ofU-shaped flexible resilient conductors having the ends of a branch ofeach rigidly supported in spaced relation and their other branchesfacing said contact surfaces of said switch blade with contact nieansthereon for engaging said contact surfaces of said switch blade, meansbiasing said contact means into high pressure contact engagement withsaid contact surfaces of said switch blade, and articulated meansmechanically interconnecting said U-shaped conductcr's for distrihiitingthe contact pressures applied by said biasing ineans through saidcontact means to said contact siirfaces. I p

22. In a switch, in ccinhiriation, a switch blade having spaced contactsurfaces and a relatively movable contact assembly nio'iint'ed ininsulated spaced relation, said contact assembly including a pair ofU-shaped flexible resilient condiictcrshaving the ends of a branch ofeach fl y cree in paced relation aria their other branches facing saidcontac surfaces of said switch blade with contact means thereon forengaging said Contact surfaces of said switch blade, means individual toeach contact means biasing the same into high pressure contactengagement with said contact surfaces of said switch blade, meanslimiting the movement of said contact means toward said contact surfacesto a distance slightly past the respective contact surface of saidswitch blade engaged by said contact means in switch closed position,and articulated means mechanically interconnecting said U-shapedconductors for distributing the contact pressures applied by saidbiasing means through said contact means to said contact surfaces.

23. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, meansindividual to each contact means biasing the same into high pressurecontact engagement with said contact surfaces of said switch blade, anequalizer bar extending past adjacent branches of said U-shapedconductors and mechanically interconnecting said biasing means todistribute the contact pres-- sures applied by said biasing meansthrough said contact means to said contact surfaces, and a loading pinextending between said adjacent branches near the bottom of the U-shapeand in spaced relation to said equalizer bar.

24. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, means biasingsaid contact means into hi h pressure contact engagement with saidcontact surfaces of said switch blade, an equalizer bar mechanicallyinterconnecting said tJ-shaped conductors to distribute the contactpressures applied by said biasing means through said contact means tosaid contact surfaces, and stop means carried by said equalizer barlimiting the movement of said contact means toward said contact surfacesto a distance slightly past the respective contact surfaces of saidswitch blade engaged by said contact means in switch closed position.

25. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, means biasingsaid contact means into high pressure contact engagement with saidcontact surfaces of said switch blade, an equalizer bar extending pastadjacent branches of said U-shaped conductors and mechanicallyinterconnecting said U-shaped conductors to distribute the contactpressures applied by said biasing means through said contact means tosaid contact surfaces, stop means carried by said equalizer bar limitingthe movement of said contact means toward said contact surfaces to adistance slightly past the respective contact surface of said switchblade engaged by said contact means in switch closed position, and aloading pin extending between said adjacent branches in spaced relationto said equalizer bar.

26. in a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and their other branches facingsaid contact surfaces of said switch blade with contact means thereonfor engaging said contact surfaces of said switch blade, means biasingsaid contact means toward each other into high pressure contactengagement with said contact surfaces of said switch blade therebetween,and an equalizer bar extending past adjacent branches of said U-shapedconductors and mechanically interconnecting said U-shaped conductors todistribute the contact pressures applied by said biasing means throughsaid contact means to said contact surfaces.

27. The invention, as set forth in claim 26, wherein the stop means is asleeve telescoped with the equalizer bar and is stressed in compressionwhen the switch blade is out of engagement with the contact assembly.

28. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said contact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and the other branches facing saidcontact surfaces of said switch blade with contact means thereon forengaging said contact surfaces of said switch blade, a leaf springoverlying each of said other branches with one end of each actingthereagainst to bias the contact means carried thereby into highpressure contact engagement with the respective contact surface of saidswitch blade, an equalizer bar extending past adjacent branches of saidU-shaped conductors and mechanically interconnecting the intermediateportions of said leaf springs, and a loading pin extending between saidadjacent branches in spaced relation to said equalizer bar with theother ends of said leaf springs bearing thereagainst.

29. in a switch, in combination, a switch blade having spaced contactsurfaces on opposite sides and a relatively movable contact assemblymounted in insulated spaced relation, said contact assembly including apair of U-shaped flexible resilient conductors having the ends of abranch of each rigidly supported in spaced relation and their otherbranches facing said contact surfaces of said switch blade with contactmeans extending transversely thereof at their outer ends for engagingopposite sides of said switch blade therebetween, each contact meanshaving a convex contact surface with the radius of the transverseportion being substantially greater than the radius of the longitudinalportion, means biasing said contact means into high pressure contactengagement with said contact surfaces of said switch blade, an equalizerbar mechanically interconnecting said other branches to distribute thecontact pressures applied by said biasing means through said contactmeans to said contact surfaces, and means mounting said switch blade toswing into and out of engagement with said contact assembly transverselyof said other branches of said U- shaped conductors and longitudinallyof said convex contact surfaces.

30. The invention, as set forth in claim 29, wherein the biasing meanscomprises leaf springs overlying the sides of the other branches awayfrom the switch blade and the equalizer bar is connected to theintermediate portions of said leaf springs.

31. The invention, as set forth in claim 29, wherein a line terminal padis connected to the contact assembly at a location where it constitutesa substantially symmetrical endwise extension of the switch blade inswitch closed position whereby the magnetic forces incident to currentflow have substantially no tendency to cause said switch blade to movetoward open position.

32. The invention, as set forth in claim 29, wherein the contactassembly comprises two pairs of U-shaped flexible resilient conductorseach arranged and constructed as aforesaid.

33. In a switch, in combination, a switch blade having a pair of spacedapart blade members provided with inwardly facing contact sw'faces and arelatively movable contact assembly mounted in insulated spaced relationwith the latter being straddled by the former, said contact assemblyincluding a pair of U-shaped flexible resilient conductors with the endsof adjacent branches rigidly supported in spaced relation and theirother branches having contact means thereon facing outwardly toward saidcontact surfaces on said blade members, spring means biasing said otherbranches outwardly and said contact means carried thereby into highpressure contact engagement with said contact surfaces of said switchblade, and an equalizer bar in .compression between said spring means todistribute the contact pressures applied by said spring means throughsaid contact means to said contact surfaces.

34. The invention, as set forth in claim 33, wherein the ends of theequalizer bar extend past the other branches and carry stop meanslimiting the outward movement of the contact means to positions slightlypast the respective contact surface of the respective blade memberengaged by said contact means in switch closed position.

35. The invention, as set forth in claim 33, wherein a loading pinextends through the adjacent branches near the bottom of the U-shape andthe ends thereof limit the movement apart of said adjacent branches whenthe switch blade is disengaged from the contact assembly.

36. The invention, as set forth in claim 33, wherein the contact meansis located near the outer ends of the other branches and the U-shapesopen in the direction of opening movement of the switch blade.

37. The invention, as set forth in claim 33, wherein the contact meansis located near the outer ends of the other branches and the U-shapesopen in the direction of closing movement of the switch blade.

38. In a switch, in combination, a switch blade having spaced contactsurfaces and a relatively movable contact assembly mounted in insulatedspaced relation, said con tact assembly including a pair of U-shapedflexible resilient conductors having the ends of a branch of eachrigidly supported in spaced relation and the other branches facing saidcontact surfaces of said switch blade with contact means thereon forengaging said contact surfaces of said switch blade, a leaf springoverlying each of said other branches with one end of each actingthereagainst to bias the contact means carried thereby into highpressure contact engagement with the respective contact surface of saidswitch blade, and the other end of each leaf spring bearing against therespective branch, an equalizer bar extending past adjacent branches ofsaid U-shaped conductors and bearing against intermediate portions ofsaid leaf springs, and a loading pin extending between said adjacentbranches in spaced relation to said equalizer .bar.

39. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other for receivingsaidswitch blade therebetween remote from the free ends thereof, springmeans interposed between the branches of each U-shaped conductor andbiasing said inner branches thereof toward each other, an equalizer barextending transversely ofsaid U-shaped conductors and connected at itsends to said outer branches, and spacer means carried by said equalizerbar and limiting the movement of said inner branches toward each other.

40. The invention, as set forth in claim 39, wherein the 24 switch bladehas diametrically oppositely extending contact ears .and is rotatableabout its longitudinal axis to move the same into and out of engagementwith the facing surfaces of the inner branches.

41. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other for receiving saidswitch blade therebetween remote from the free ends thereof, a loadingpin between said free ends of said inner branches limiting the movementthereof toward each other, spring means interposed between the branchesof each U-shaped conductor and biasing said inner branches thereoftoward each other, an equalizer bar extending transversely of saidU-shaped conductors and connected at its ends to said outer branches,and spacer means carried by said equalizer bar and limiting the movementof said inner branches toward each other.

42. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other for receiving saidswitch blade therebetween remote from the free ends thereof, a loadingpin between said free ends of said inner branches limiting the movementthereof toward each other, a leaf spring interposed between the branchesof each U-shaped conductor having the central portion reacting againstthe inner side of the respective outer branch and the ends reactingagainst the inner side of the respective inner branch, an equalizer barextending transversely of said U-shaped conductors and said centralportions of said leaf springs and connected at its ends to said outerbranches, and a spacer sleeve carried by said equalizer bar and limitingthe movement of said inner branches toward each other.

43. In a switch, in combination, a switch blade and a relatively movablecontact assembly mounted in insulated spaced relation, said contactassembly including a pair of U-shaped flexible resilient conductorshaving the ends of their outer branches rigidly supported in spacedrelation and their inner branches facing each other for receiving saidswitch blade between the free ends thereof, spring means interposedbetween the branches of each U-shaped conductor and biasing said innerbranches toward each other, andan equalizer bar extending transverselyof said inner branches and interconnecting said spring means, saidswitch blade having diametrically oppositely extending contact ears andbeing rotatable about its longitudinal axis to move the same into andout of engagement with the facing surfaces of said inner branches.

44. The invention, as set forth in claim 43, wherein the stop meanscooperate with the free ends of the inner branches and limit themovement thereof toward each other when the contact ears of the switchblade are disengaged therefrom.

References Cited in the file of this patent UNITED STATES PATENTS2,256,734 Cornell et al Sept. 23, 1941 2,546,366 Lindae Mar. 27, 19512,733,322 Curtis Jan. 31, 1956 2,760,034 Kowalski et al. Aug. 21, 19562,818,474 Gussow Dec. 31, 1957

